Biscyanoacrylates and their production have been known for some time. They are produced by at least the following two methods:
In the Knoevenagel condensation, formaldehyde is reacted with biscyanoacetates to form a crosslinked polymer which cannot readily be thermally depolymerized. PA1 In the Retro-Diels-Alder reaction, a monofunctional cyanoacrylate is first blocked with dienes. The blocked monofunctional cyanoacrylate is hydrolyzed to the free acid. The ester is then prepared from the corresponding acid chloride with a diol. Finally, after the biscyanoacrylate has been exchanged for maleic anhydride, the pure biscyanoacrylate is obtained after repeated recrystallization from benzene. Accordingly, this method of production comprises five stages and is thus uneconomical.